add CHANGES entry for embed

Reviewed-by: Rich Salz <rsalz@openssl.org>

CHANGES

@@ -3,6 +3,27 @@
  _______________
 
  Changes between 1.0.2 and 1.1.0  [xx XXX xxxx]
+
+  *) New ASN.1 embed macro.
+
+     New ASN.1 macro ASN1_EMBED. This is the same as ASN1_SIMPLE except the
+     structure is not allocated: it is part of the parent. That is instead of
+
+     FOO *x;
+
+     it must be:
+
+     FOO x;
+
+     This reduces memory fragmentation and make it impossible to accidentally
+     set a mandatory field to NULL.
+
+     This currently only works for some fields specifically a SEQUENCE, CHOICE,
+     or ASN1_STRING type which is part of a parent SEQUENCE. Since it is
+     equivalent to ASN1_SIMPLE it cannot be tagged, OPTIONAL, SET OF or
+     SEQUENCE OF.
+     [Steve Henson]
+
   *) Remove EVP_CHECK_DES_KEY, a compile-time option that never compiled.
      [Emilia Käsper]